1. Field of the Invention
The present invention relates to an image reading apparatus (e.g., a scanner, a copier, and a facsimile) that includes a multifeed (MF) detecting function using an ultrasonic (US) sensor, and a multifeed determining method and a multifeed determining program.
2. Description of the Related Art
In a technology described in Japanese Patent Application Laid-open No. H05-40030, as a threshold (MF determination slice) of MF determination performed in an MF detecting function using an US sensor, a fixed value is set by taking into consideration cardboards with which an output of the US sensor becomes low.
However, according to the conventional technology, there is a problem that because the fixed value is set as the MF determination slice by taking into consideration cardboards with which an output of the US sensor becomes low, the MF determination slice is low in a case of thin paper and MF detection accuracy is thereby insufficient.